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Python class constructor function

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Python class constructor is used to initialize the instance of the class. Python has __init__() constructor function for the Python classes.

The method __init__( ) executes every object creation of that class. It’s a special method or member function of a class that automatically gets executes on every object creation. It is always called when an object is created.

Syntax of constructor declaration :

def __init__(self):
    # body of the constructor

The def keyword is used to define function.

Types of constructors

Examples Class Constructor in Python

Simple example code. Constructors also verify that there are enough resources for the object to perform any start-up task.

Creating Default Constructor Python class

This constructor has the same name as the class name.

class Test:
    num = 0

    def __init__(self):
        self.num = 100
        print(f'Object has created!')
        print(self.num)


# creating object
obj = Test()

Output:

Python class constructor function

Creating Parameterized Constructor

The constructor may have any number of parameters. Let’s see an example with single parameters.

class Test:
    i = 10

    def __init__(self, value):
        self.i += value
        print(self.i)


# creating object
obj = Test(10)

Output: 20

Counting the number of objects in a class

Let’s count how many times objects are created for any class.

class Students:
    count = 0

    def __init__(self):
        Students.count += 1


s1 = Students()
s2 = Students()
s3 = Students()
print("The number of students:", Students.count)

Output: The number of students: 3

Do comment if you have any doubts or suggestions on this Python class tutorial.

Note: IDE: PyCharm 2021.3.3 (Community Edition)

Windows 10

Python 3.10.1

All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.

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